1. Field of the Invention
The present invention relates to a controlling device, and more particularly to a controlling device for a body support pivotally mounted on top of a stool. The controlling device includes a ratchet gear and two pawls respectively and selectively engaged with one tooth of the ratchet gear so as to control pivotal direction of the body support.
2. Description of Related Art
Professionals such as medical personnel and dentists often require a specialized seating so that when the occupant is seated on the specialized seating, a portion other than the buttocks of the occupant""s body is also supported. Because these specialized people often need to bend their bodies to perform a certain procedure on the patient, the bending portion of the user""s body will gradually deform and thus the user will experience an occupational hazard if the bending body portion is not supported. For example, the dentist often leans forward to the patient to perform medical treatment on the patient lying on the couch or chair. After a long period of time without any support to the back, the dentist will be troubled by back disorders. To solve the problem, a chair with a support is introduced to the market so that the user is able to have support either to the abdomen or the back of the user""s body. However, the support on the chair is fixed so that the entry and exit of the chair is difficult for the user. Again, to obviate the drawback, an invention is introduced to the market. The invention was issued patent on Mar. 30, 1999 to Joseph Hannes, Franklin bearing the Ser. No. 5,887,948.
Referring to FIGS. 6, 7 and 8 of the patent, it is noted that the ratchet mechanism of the invention includes a casing (70) defining therein a space (80), a pawl (170) pivotally received in the casing (70) and a ratchet gear (90) securely attached to a distal end of a shaft (50) and having multiple ratchet teeth (96) thereon. After the assembly of the invention, the user is able to control the pivotal direction of the support 36 (as shown in FIG. 1) by engaging the distal end (174) of the pawl (170) with one tooth of the ratchet mechanism (90). When the distal end of the pawl (170) engages with one tooth of the ratchet mechanism (90), it is clearly seen from FIG. 8 that the support (36) can only be pivoted counterclockwisely. When the support (36) is to be pivoted clockwisely, due to the secure engagement of the distal end (174) of the pawl (170) to the ratchet mechanism (90), the support (36) is firmly fixed and can not be pivoted clockwisely. However, when the user releases the engagement between the distal end (174) of the pawl (170) and the ratchet mechanism (90), the support (36) is able to be freely rotated relative to the seat (32) (as shown in FIG. 1).
This kind of support member mounted on a seat does solve most of the problems for the specialized personnel. However, because the support can only pivot in one fixed direction, it is still inconvenient for the user. When the dentist, for example, is attending a patient lying on the bed on one side of the dentist, this conventional support member is able to provide sufficient support to either the abdomen or the back of the dentist. When the dentist must alternately attend two patients lying on two opposite sides of the dentist, the support member hinders the movement of the dentist. That is, the dentist will have to release the lock of the pawl (170) to the ratchet gear (90) to freely rotate the support (36) and when the support (36) is re-positioned at an appropriate position, the user will then have to engage the pawl (170) to the ratchet gear (90) so as to lock the position of the support (36) relative to the seat (32). Then, the user will have to alternately adjust and readjust the support (36) relative to the seat (32), which is too troublesome and too time consuming.
To overcome the shortcomings, the present invention tends to provide an improved controlling device to mitigate and obviate the aforementioned problems.
The primary objective of the present invention is to provide an improved controlling device for a body support pivotally mounted on top of a stool. With the controlling device, the controlling device enables the user to move only a knob so as to control the pivotal direction of the body support.
Another objective of the present invention is to provide a ratchet gear and two pawls selectively engaged with one tooth of the ratchet gear so as to control the pivotal direction of the body support.
Still, another objective of the present invention is that means, such as a wedge, for alternatively activating either one of the pawls is provided in the controlling device so that the user is able to use the controlling device to change the pivotal direction of the support.
In order to accomplish the foregoing objective, the controlling device for a support pivotally mounted on top of a stool includes a housing adapted to securely engage with a bottom face of the support;
two pawls pivotally received in the housing;
means for activating movement of either one of the pawls; and
a ratchet gear received in the housing,
whereby after either one of the pawls is activated, the activated pawl is able to selectively engage with the ratchet gear so that the support is able to pivot in a predetermined direction.
An advantageous feature of the present invention is that the housing is composed of a top cover, a body and a bottom cover.
An advantageous feature of the present invention is that the bottom cover has two protruding posts respectively mounted on opposite sides of the bottom cover to correspond to the two pawls and two positioning rods each being formed close to a corresponding one of the protruding posts.
An advantageous feature of the present invention is that each pawl has a first end, a hole and a spring having a first end securely connected to the first end of the pawl and a second end securely connected to a corresponding one of the positioning rods so as to provide a recovery force to the corresponding pawl after a corresponding one of the protruding posts extends into the hole of the pawl.
An advantageous feature of the present invention is that the activating means comprises a wedge pivotally received in the housing to control the movement of the pawls.
An advantageous feature of the present invention is that the activating means further comprises a control knob pivotally mounted on the housing and opposite to the wedge.
An advantageous feature of the present invention is that the ratchet gear is formed on top of an extension which is adapted to be received the tube and has an indentation longitudinally defined in a periphery of the extension to receive therein a rectangular head, the rectangular head is formed with a threaded bolt which is extendable into the tube so that the rectangular head is received in the indentation and thus the extension is able to be adjustably moved relative to the tube.